Apparatus for coupling a multiple emitter laser diode to a multimode optical fiber
First Claim
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1. In combination:
- a laser diode bar having a plurality of emitter regions having output facets,a microlens comprising an optical fiber having an axis oriented substantially perpendicular to and positioned in the emission path of radiation from said emitter regions to be optically coupled thereto and spaced therefrom by a distance of approximately one focal length of said microlens,a plurality of optical fibers equal to the number of emitter regions of said laser diode bar, and oriented on axis with respect to said microlens such that radiation from said individual ones of said emitter regions is optically coupled into individual ones of said plurality of optical fibers.
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Abstract
A small diameter multimode optical fiber with a low numerical aperture (i.e., 0.1) is used as a microlens to collimate the output emissions of a laser diode before butt coupling the output of the laser diode to an optical fiber. The optical fiber used as the microlens is chosen such that its diameter roughly equals the diameter of the fiber to be coupled to the laser diode. The collimation is performed in the high NA direction of the output of the laser diode. The output of a bundle of butt coupled optical fibers may be used to pump a laser system.
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Citations
42 Claims
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1. In combination:
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a laser diode bar having a plurality of emitter regions having output facets, a microlens comprising an optical fiber having an axis oriented substantially perpendicular to and positioned in the emission path of radiation from said emitter regions to be optically coupled thereto and spaced therefrom by a distance of approximately one focal length of said microlens, a plurality of optical fibers equal to the number of emitter regions of said laser diode bar, and oriented on axis with respect to said microlens such that radiation from said individual ones of said emitter regions is optically coupled into individual ones of said plurality of optical fibers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In combination:
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a laser diode bar having a plurality of emitter regions, a cylindrical microlens comprising an optical fiber positioned in the emission path of radiation from said emitter regions and spaced therefrom by a distance approximately equal to where R is the radius of and n is the index of refraction of said microlens, a plurality of optical fibers equal to the number of emitter regions of said laser diode bar, and oriented with respect to said microlens such that radiation from said individual ones of said emitter regions is optically coupled into individual ones of said plurality of optical fibers. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A diode pumped laser system, including:
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cavity forming means, including an active laser medium, a laser diode bar having a plurality of emitter regions, a microlens comprising an optical fiber having an axis oriented substantially perpendicular to and positioned in the emission path of radiation from said emitter regions to be optically coupled thereto and spaced therefrom by a distance of approximately one focal length of said microlens, a plurality of optical fibers equal to the number of emitter regions of said laser diode bar each of said plurality of optical fibers having a first end and a second end, each of said first ends oriented on axis with respect to said microlens such that radiation from said individual ones of said emitter regions is optically coupled into individual ones of said plurality of optical fibers, said second ends of each of said plurality of optical fibers arranged in a bundle, means for optically coupling radiation from said bundle into said laser cavity.
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20. A diode pumped laser system, including:
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cavity forming means, including an active laser medium, a laser diode bar having a plurality of emitter regions, a microlens comprising an optical fiber having an axis oriented substantially perpendicular to and positioned in the emission path of radiation from said emitter regions to be optically coupled thereto and spaced therefrom by a distance of approximately one focal length of said microlens, a plurality of optical fibers equal to the number of emitter regions of said laser diode bar each of said optical fibers having a first end and a second end, each of said first ends oriented on axis with respect to said microlens such that radiation from said individual ones of said emitter regions is optically coupled into individual ones of said plurality of optical fibers, said second ends of each of said plurality of optical fibers arranged in a bundle, means for optically coupling radiation from said bundle into one end of said laser cavity.
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21. A diode pumped laser system, including:
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a bar of active solid state laser material disposed in a laser cavity having opposing ends, one face of said bar forming a first one of said opposing ends, a laser diode bar having a plurality of emitter regions, a microlens comprising an optical fiber having an axis oriented substantially perpendicular to and positioned in the emission path of radiation from said emitter regions to be optically coupled thereto and spaced therefrom by a distance of approximately one focal length of said microlens, a plurality of optical fibers equal to the number of emitter regions of said laser diode bar each one of said plurality of optical fibers having a first end and a second end, each of said first ends oriented on axis with respect to said microlens such that radiation from said individual ones of said emitter regions is optically coupled into individual ones of said plurality of optical fibers, said second ends of each of said optical fibers arranged in a bundle, means for optically coupling radiation from said bundle into said first end of said laser cavity.
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22. A method of coupling the output of a laser diode emitter region into the end of an optical fiber including the steps of:
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optically coupling the output radiation of said laser diode emitter region into a microlens comprising an optical fiber, said microlens spaced from said laser diode by about ##EQU2## where R is the radius of and n is the index of refraction of said microlens, said microlens having a diameter about 20% to 50% larger than the lateral dimension of said emitter region, optically coupling the output radiation of said microlens into the end of an optical fiber, said optical fiber having a diameter about equal to the diameter of said microlens, said end of said optical fiber spaced as close as possible to said microlens, said optical fiber having a numerical aperture about equal to the numerical aperture of said emitter region of said laser diode in its low direction.
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23. A method of coupling the output of the emitter regions of a plurality of laser diodes into a fiber optic bundle including the steps of:
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optically coupling the output radiation of said each of said emitter regions into a different region of a microlens comprising an optical fiber, said microlens spaced from each of said emitter regions by a distance of about where R is the radius of and n is the index of refraction of said microlens, said microlens having a diameter about 20% to 50% larger than the lateral dimensions of said emitter regions, separately optically coupling the output radiation of said microlens corresponding to the output of each of said emitter regions into the ends of different ones of a plurality of optical fibers, each of said optical fibers having a diameter about equal to the diameter of said microlens, the ends of said optical fibers spaced as closely as possible to said microlens, said optical fibers having a numerical aperture about equal to the numerical aperture of said emitter regions of said laser diode in its low direction. - View Dependent Claims (24)
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25. In combination:
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a laser diode having an emitter region having an output facet, a microlens comprising an optical fiber oriented substantially perpendicular to and positioned in the emission path of radiation from said emitter region to be optically coupled thereto and spaced therefrom by a distance of approximately one focal length of said microlens, an optical fiber oriented on axis with respect to said microlens such that radiation from said emitter region is optically coupled into said optical fiber. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33)
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34. In combination:
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a laser diode having an emitter region, a cylindrical microlens comprising an optical fiber positioned in the emission path of radiation from said emitter region and spaced therefrom by a distance approximately equal to where R is the radius of and n is the index of refraction of said microlens, an optical fiber oriented on axis with respect to said microlens such that radiation from said emitter region is optically coupled into said fiber. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42)
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Specification